Headlamps are used to light the space in front of a vehicle. Over the years, headlamps have used acetylene, electric current, halogen, high-intensity discharge systems, and other methods to illuminate a lamp. Many of today's headlamps use light-emitting diodes (LEDs) as a light source. LEDs are relatively inexpensive and bright, making them an ideal candidate for a headlamp light source in some respects. However, differences between LEDs and other light sources create a need for additional engineering.
For example, LEDs may not generate as much heat as incandescent bulbs. Slight changes in temperature may provide some positive effects but may also lend themselves to further considerations. Lower temperatures may generally equate to less wasted energy, adding to the overall efficiency of the vehicle. Additionally, as LEDs may not experience “burn out,” they may need replacing much less frequently. For example, a particular lamp may last an entire effective life of a vehicle. However, because the source of light may generate less heat, the average temperature inside a headlamp can be lower with an LED, and the headlamp may tend to develop condensation inside its lamp housing. That is, the bulb may not raise the temperature inside lamp housing sufficiently above the dew point temperature to evaporate moisture in the air within the housing.
Regardless of the type of light source within a headlamp, its particular structure may affect its propensity to develop condensation. Generally, surfaces near the light source will see higher temperatures than surfaces farther away as energy radiates from the source. Moreover, particular internal structures of various bulbs will tend to cause more or less airflow within the headlamp. Increased airflow can generally lead to more uniform airflow distributions and less condensation for a given light source. Thus, areas of low flow can be more susceptible to higher levels of condensation. Accordingly, a need exists for alternative lamp assemblies that permit less condensation.